2.5 Available freshwater bivalves data for France
In order to compare the data collected with freshwater bivalves eDNA metabarcoding, data provided by INPN were used. INPN (Inventaire national du Patrimoine naturel, National Inventory of the NAtural Heritage)  is a system implemented to ensure in a standardized way the restitution of synthetic data needed for the expertise, the development of conservation strategies and the dissemination of information and national and international reports relatied to the French natural heritage (plant and animal species, natural habitats and geological heritage, seehttps://inpn.mnhn.fr/accueil/presentation-inpn?lg=en, and Gargominy, Léonard, Prié and Cucherat, 2016). The information comes from many national programs and data provided by various partners. INPN ensure the validation of this data on three levels (1) conformity, e.g. the species is referenced in the French taxonomic register (Gargominy et al., 2019) and the observation is situated in France; (2) consistency, e.g. observation is not dated after the integration of the data; (3) scientific validation, e.g. marine species is not recorded on land.
INPN thus includes data provided in the literature (grey as well as academic), in museum collection as well as observations through various programs. About 32 900 freshwater bivalve data are available on the INPN database in 2020. For focused species of conservation concern, the Giant Freshwater Pearl Mussel Pseudunio auricularius (Spengler, 1793), the Depressed River Mussel Pseudanodonta complanata (Rossmässler, 1835), the Nut Orb Mussel Sphaerium rivicola (Lamarck, 1818) and the Witham Orb Mussel S. solidum (Normand, 1844), a distinction was made between ancient data (i.e. here data collected before the year 2000) and recent ones. Shell-only data were considered as ancient data.